This invention relates, in general, to analog-to-digital converters, and more particularly, to monolithic integrated analog-to-digital converters having I.sup.2 L-linear circuitry and method of making same.
Analog-to-digital (A-to-D) converters are widely used in the electronics industry for quantizing analog voltages to discrete levels thereby permitting further processing utilizing digital circuitry. In the past, this A-to-D conversion has often presented troublesome design problems, and many schemes for performing this conversion have been set forth in the electronics literature. Furthermore, these A-to-D converters, when compared with other portions of most digital processing circuitry, are generally complicated, involving several device types. As a result, an integrated A-to-D converter tends to use a large amount of semiconductor substrate area in comparison to the rest of the digital processing circuitry.
Therefore, it can be appreciated that an A-to-D converter which is simple in concept, requiring only a few devices, and requiring a relatively small area on a semiconductor chip is highly desirable.